Knockholt landfill gets five-year expansion

When you climb 170,000 tonnes of buried Bulkley Valley garbage, you get a great view.

Knockholt landfill, about 12 km east of Houston, is the last stop for all trash collected in the six towns from Smithers to Southside.

And standing on its breezy top last Tuesday, it’s clear the site is extra busy this summer.

Below, surveyors, excavators and pipe fitters were laying the base of a $200,000 expansion “cell” that will hold the next five years’ worth of garbage in a landfill expected to last until at least 2063.

Ahead, a giant compactor with spiky steel wheels mashed a fresh layer of garbage, careful to avoid a pipe exhausting methane from the 12 years worth of garbage buried beneath it.

And hundred of metres away, a worker measured outflow from the complex system of pipes, drain rock and clay liner that runs throughout the landfill, collecting any rain or garbage ooze that leaches out the landfill and channeling it through an artificial wetland full of toxicity-depleting cattails.

A bird hunts for bugs among the toxicity-depleting cattails planted in an artificial wetland at the Knockholt landfill.

But no matter how well Knockholt develops—its artificial wetland won a water-treatment award in 2010—Bill Miller, chair of the Regional District of Bulkley-Nechako, says landfilling is always a last resort.

“It’s expensive,” he says. “And it has long-term ramifications.”

At $3.2 million, waste handling cost$800,000 more than any other service in the RDBN last year.

Miller said it regularly tops the RDBN budget, largely because of the district’s long hauling distances.

Some small innovations help to keep the costs from rising further.

Miller pointed out that the RDBN uses loaded rock trucks to compact the clay liner in new development areas, and they stagger their wheel patterns when running over different sections—a driving technique that avoids the need for extra compactor equipment.

Except for the drain rock that surroundings its collector pipes, the landfill also uses on-site clays for capping, as well as waste wood composted in the landfill’s septage receiving bed.

But recycling is still the biggest cost-cutter.

Less waste at existing landfills delays the expensive and task of siting and constructing new ones, Miller said.

“We’ve really been pushing for cardboard recycling because it’s such a high volume,” he said.

A 2008 audit shows paper and cardboard make up about 20 per cent of all waste in the RDBN. Only organic material, at nearly 33 per cent, ranks higher in the breakdown.

But while the RDBN does have an increasing number of recycling depots, and is aiming for more, on Tuesday it was easy to spot piles of cardboard and scrap metal getting crunched under the landfill compactor wheels.

“We have tipping fees for construction and demolition waste—they’re currently at $60 a metric tonne—and it still doesn’t completely deter people from dumping metal products and other things that could be properly recycled.”

A worker installs a new leachate collector pipe at the expanding Knockholt landfill on Friday, Aug. 3.

Junk science

An environmental engineer, Dougall wrote her UBC Master’s thesis on landfills.

So Dougall is happy to talk trash at Knockholt, from its moisture content (relatively dry) to its density (air-tight enough that its last underground fire was years ago).

Just don’t call the place a dump.

“These are fully engineered facilities, and there’s a lot of science that goes into these” Dougall says.

“I get very agitated when I hear ‘dump,'” she added, laughing.

Knockholt graduated from dump to landfill in 1998. That’s when engineers capped the original landfilling area under clay and topsoil, then built the landfill’s first leachate collector system.

But the most innovative change came in 2007, when the RDBN built Knockholt’s artificial wetland.

When water flows down the long, clay-lined pool of the wetland, it filters through six berms planted full of cattails.

Dougall explained that it’s actually bacteria in the cattail roots that remove pollutants.

All the leachate is tested before it flows from a 15,000 cubic-metre collector pool into the wetland and out into the ground.

B.C.’s environment ministry limits outflow from the landfill to 100 cubic metres a day, and it only happens during spring and summer when the ground isn’t frozen.

Groundwater is regularly tested at the Knockholt site. The Bulkley River, 800 meters away at its closest point, is also tested above and below the landfill area twice a year.

Given that Knockholt is a fairly young , low-volume landfill, Dougall said its leachate is relatively easy to treat.

But if pollutant levels do rise, Dougall said the RDBN has room to install a second wetland area, and they may bring in a solar-powered aerator machine to speed things along.

“There’s always risk,” Dougall said. “But we’re managing it the best way possible with today’s technology and understanding.”

A bulldozer levels a fresh load of garbage before it’s buried.

A fair deal on recycling

By 2014, the B.C. government plans to bring in new product stewardship rules that will force industry to pick up the tab to collect and recycle 70 per cent of all their paper and packaging materials.

That could mean new recycling depots in the RDBN, as well as curbside recycling for every town that now has garbage pick-up.

“The stewardship program is really going to help—if we have them in our areas,” Dougall said.

It’s a big “if.”

The RDBN and other local governments in northern B.C. worry that, with their high transportation costs, industry may choose to simply write off their districts as part of the 25 per cent they don’t need to collect.